Buffer device for rock-drills.



Nuo. 7||,998. Patented Oct. 28, |9072.

R.. B. MCCNNEY.

BUFFER DEVICE FOR ROCK DHILLS.

(Application med Dc. 28, 1901.)

(No Model.)

iii

UNITED STATES PATENT OFFICE.

ROBERT B. MCCONNEY, OF DENVER, COLORADO, ASSIGNOR TO THE MINE SMELTER SUPPLY COMPANY, OF DENVER, COLORADO, A CORPORATION OF COLORADO.

BUFFER DEVICE FOR RocK-DR-ILL'S.

SPECIFICATION forming part of Letters Patent No. 711,998, dated October 28, 1902.

I l Application filed December 28, 1901. Serial No. 87,5 72. (No model.)

T' @ZZ whom, t may concern:

Be it known thatI, ROBERT B. MCCONNEY, a citizen of the United States of America, residing at Denver, in the county of Arapahoe and State of Colorado, have invented certain new and useful Improvements in Buffer Devices for Rock-Drills; and I do declare the following to be a full, clear, and exact description of the invention, such as will enable othxo ers skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to the letters and figures of reference marked thereon, which forma part of this specification.

My invention relates to improvements in buffer devices for rock-drills, and my invention is designed more especially as an improvement on the buer device of the drillholding bar of the rock-drill patented on the zo 28th day of May, 1901, No. 675,202.

The object of this invention is to provide an improved means for cushioning the recoil of the drill-holder, and I lattain this object by dispensing with the adjustable abutment z5 shown in that patentgvhich was designed to receive the force of the recoil blow of the said drill-holder and in its place to form integral with the drill-casing a solid abutment-collar which is provided with a central bore to re- 3o' ceive the rear end of the drill-holder and against which one end or' the main bufferspring, which encircles the drill-holder, bears, the other end of said buffer-spring bearing against a washer, which is held against the 3 5 tension -of the buffer-spring by an annular band or ring formed integral with the inner periphery of the drill-casing, against which the washer is normally pressed by the expansive force of the buer-spring, the said 4o washer being designed to be struck by an abutment-collar secured upon the drill-holder as the said drill-holder is caused to recoil from its forward blow, thus compressing the buffer-spring against the solid abutment or wall and cushioning the recoil of the drillholder.

In the patent above referred to the main buer-spring was shown as being shorter than the distance between the adjustable abut- 5o ment and the abutment-collar carried by the drill-holder. Hence the spring was normally relaxed, and it was found in the running of the drill that the springs repeated compression movement against its abutment, which was caused by the repeated recoil blow of the 5 5 drill-holder against it and against its adjustable abutment, acted as so man v direct blows against the spring and caused the spring to rapidly crystallize and to break, necessitating the frequent replacing ofthe spring by a 6o new one, which in its turn would last but a short time. In my improved arrangement the spring is normally held slightly compressed between a washer and a solid abutment-collar and the concussion of the drillholder against it and of thespring against its yabutment is entirely obviated, and consequently the liability' of crystallization and subsequent breakage by the recoil movement of the drill-holder is practically obviated.

In the accompanying drawings, Figure l is a plan View of a rock-drill embodying my improvement, a portion of the casing being shown in section; and Fig. 2 is a vertical longitudinal sectional View thereof.

Like letters and figures of reference indicate corresponding parts.

Referring to the drawings, the numeral l indicates the drill-casing, and 2 the shell which supports the casing and in which the 8o casing has an endwise-sliding movement. The casing is moved back and forth by a feed-screw 3, which revolves in an elongated nut 4, carried by the under side of the casing, the said screw being revolubly secured 85 at one end to the shell, while the other end has clamped thereto a handle by which the said screw is revolved. The forward end of the casing has a central bore which is threaded and receives a nut 5, bored centrally to 9o receive the forward end of the drill-shaft A. The, rear end of the casing is centrally bored and receives a nut 6, having a central bore which is spirally Iiuted and in-whichreciprocates the rifle-bar 7, which is screwed into 95 the rear end of the drill-shaft and which causes the intermittent revolution of the drill-holder, as will be fully understood by reference to the former patent. A crank-lever 8 is pivoted in the casing above the drillroo holder A and about centrally of the same. This lever is made up of a member 9, which is horizontally disposed and is provided with an open-ended slot l0, and a vertically-depending member 11, which is formed into a yoke, the members 12 of which straddle the drill-holder and are each provided with an open-ended slot. The slot 10 of member 9 carries a sliding box 13, in which revolves the wrist-.pin 14 of a crank-shaft 15, the said shaft carrying a {1y-wheel 16 at one end and a beveled pinion 17 at its other end, the said pinion beingdesigned to receive motion from a corresponding beveled pinion on the end of a flexible shaft, which is driven by any preferred motive power, the pinion, shaft, and means foroperating the same not beingshown.

The drill-holder is provided centrally with a cross-head 18A, having lateral trunnious which are housed in sliding boxes carried by the slots 'in members 12 of the crank-lever 8, and the cross-head is held centrally of the drill-holder by springs 18, which bear one on one side of the cross-head and one on the other side, their opposite ends bearing against collars 19 and 20, carried by the drill-holder A.

The parts thus far mentioned are all clearly shown and described in the patent above referred to, and a more extended description thereof is deemed unnecessary, as they form no part of my present invention, the object of which is to more gradually and effectively cushion the recoil blow of the drill-holder and at the same time prevent frequent breaking of the main buer-spring.-

Near the rear end of the interior of the drillcasing 1 is located an abutment collar or wall 21, which is formed integral with the casing. This abutment-collar is provided with acentral bore 22, which is in axial alinement with the bores in the nuts 5 and 6 at the front and rear ends, respectively, of the casing, and within this bore 22 the rear end of the drillholder is supported. At a suitable distance forward of the abutment the casing is provided with an annular projection or rim 23, which is formed integral with the said casing and which is for a purpose to be hereinafter explained.

The drill-holder A is of three diiferent diameters. The forward portion, which is practically a third of its length, is of the greatest diameter, and at the junction of the forward and central portions, which is next in diameter, a short taper or shoulder is formed upon which the collar 2O iits. This collar 2O is held in place by the adjacent spring 18, which is held slightly compressed between the said collar 20 and one side of the cross-head 18A. At the junction of the central and rear portions of the drill-holderashort taper or shoulder is formed upon which the collar 19 ts, and the collar 19 is held against rearward movement by a sleeve 24, which surrounds the drill-holder from the collar 19 to the rear end thereof, where it is held in place by a flange on the shank of the rifle-bar '7. A

washer 25 is slid upon the sleeve at the rear' end of the drillholder and lies normally against the annular rim 23, and between this washer and the abutment 2l is interposed a buffer-spring 26, which fits loosely around the sleeve l24 and is held slightly compressed. Now as the drill-holder is carried forward through the medium of cross-head 18A, cranklever 8, and crank-shaft 15 its rear end, which is surrounded by sleeve 2-ft,will slide smoothly through bore 22 in abutment 2l'and through buifer-spring 26 and washer 25 and when the drill-holder is carried to the limit of its forward stroke, as when the drill strikes a seam, the collar 2O will strike a spring 27, which loosely encircles the forward portion ofthe drill-holder and bears-against the nut 5, and the stroke will thus be cushioned; but on the recoil the drill-holder is always carried to the limit of its movement and the stroke is cushioned in the following manner: When the drill-holder on its recoil has reached a point about midway between the limits of its forward and rear movement, its collar 19 will strike washer 25, which is normally held against rim. 23 by buer-spring 26, and the washer will be carried rearward against the expansive pressure of spring 26, thus compressing the said spring against the abutment collar or wall 21, which will effectively cushion the recoil of the said drill-holder. As the drill-holder moves forward again the expansion of spring 26 will force washer 25 forward until it is stopped by the rim 23, in which position it is held until struck by collar 19 at each recoil of the drill-holder.

It will thus be seen that in my improvement I have provided a very simple, eective, and inexpensive means for cushioning the recoil of the drill-holder, and while I attain this object in the manner described I also reduce the breakage of the buffer-springs to a minimum, as when the said spring is normally held underv pressure, as in the present invention, lit isfar less liable to be broken when suddenly compressed by the recoil of the drillholder than when normally relaxed, as shown in the patent above referred to.

Having thus fully described my invention and the manner of its operation, what I claim as new, and desire to secure by Letters Patent, is-

1. In a recoil buffer device for rock-drilling engines, the combination with the casing, the crank-arm and the drill-holder, of an abutment-collar mounted on said drill-holder, a sleeve mounted ou said drill-holder and bearing at one end against said abutment-collar, means for securing said sleeve on said drillholder and for holding said sleeve against said collar, a fixed collar extending transversely across said casing, an axial bore in said collar surrounding loosely said sleeve, a second transverse abutment in said casing adjacent to said drill-holder abutment-collar arranged to allow said drill-holder collar to pass it during the reciprocating action of said drill- IOO IIO

holder, a washer loosely mounted on said sleeve adjacent to said second-named abutment and a compressive coiled spring mounted loosely on said sleeve and arranged under slight expansive tension between said firstnamed collar-abutment of said casing and said Washer, whereby said Washer is held against the casings second-named abutment in the path of the -recoil movement of said drill-holders abutment-collar, substantially as described.

2. In a recoil bumper device for rock-drills, the combination of the casing, the crank-arm, the cross-head, the drill-holder and the drillholders actuating-springs, and the actuatingsprings abutment-collars of the two transversely-arranged'abutment-collars arranged at a short distance apart at the rear end of said drill -holder, and axial apertures arranged concentric to said drill-holder, the sleeve secured between the rear end of said drill-holder and the rear abutment-collar of said drill-holder, the washer mounted loosely on said sleeve and the coiled compressionspring arranged and adapted to bear at one end against one of said casings abutment-collars and to expansively hold said washer ,l

against the other, substantially as described.

3. In a recoil buffer device for rock-drills, the combination with the casing and the drillholder having an abutment-collar adjacent to its rear end, of the two transverse abutment-collars cast integral with said casing and arranged a short distance apart and one of which is arranged adjacent to the normal position of said drill-holders abutment-collar, the sleeve secured to said drill-holder and arranged to bear against said drill-holders abutment-collar, the washer mounted loosely on said sleeves and the compressive spring arranged expansively between the rear abutment-collar of said casing and said washer, substantially as described.

In testimony whereof I affix my signature in presence of two witnesses.

ROBERT B. MCCONNEY.

Witnesses: g

G. SARGENT ELLIOTT, EDWIN J. MOORE. 

